More from WebMD

Sept. 6, 2011 -- Older adults who have thinking and memory problems known as cognitive impairment are at a higher risk of death, new research has found.

"The association between cognitive impairment and death risk was found even for mild impairment," says Greg A. Sachs, MD, professor of medicine and a scientist at the Center for Aging Research at Regenstrief Institute, Indiana University School of Medicine.

"When the impairment was moderate to severe, the impact on death risk was as great as [for] many chronic conditions, like congestive heart failure and diabetes," he tells WebMD.

The link has been studied for about a decade, Sachs tells WebMD. The new study strengthens the association even more, says Sachs, who is also division chief of general internal medicine and geriatrics at the university. It's a link, not proven cause and effect.

About 5.4 million Americans have Alzheimer's disease, according to the Alzheimer's Association.

The study was funded by the federal Agency for Healthcare Research and Quality. It is published in the Annals of Internal Medicine.

Memory Problems and Death Risk: Study Details

Sachs studied 3,957 men and women, aged 60 to 102. They were screened at primary care doctors' appointments. The evaluations started between January 1991 and May 1993.

The researchers asked 10 questions to assess mental status. Depending on the results, they classified the men and women as having no cognitive impairment, mild, moderate, or severe impairment.

When the impairment is mild, a person has some trouble with attention, language, judgment, memory, reading, and writing. When it progresses and is severe enough to interfere greatly with daily activities, it is termed dementia. Someone with mild impairment, for instance, can't remember appointments or the name of someone newly met.

At the start of the study, 3,157 had no mental impairment, 533 had mild impairment, and 267 had moderate to severe problems.

Sachs' team followed up to see who had died by Dec. 31, 2006.

By the end of the study, 57% of those with no impairment died. But 68% of those with mild and 79% of those with moderate to severe memory problems died.

The median survival time (half longer, half less) was 138 months for those who had no impairment. It was 106 for those with mild impairment. It was 63 months for those with moderate to severe impairment.

The study, like most, had some limitations. The men and women were only tested at the start. Memory and thinking problems were not tracked over time.

All patients were from Indianapolis. They tended to have low education and low socioeconomic status. For that reason, the findings may not apply to everyone.

However, Sachs says the findings are a reminder that cognitive impairment is important for doctors to evaluate. He says some doctors, as well as patients, dismiss problems with memory and thinking as just inevitable with age.

It needs as much attention as doctors typically pay to screening for heart disease and cancers, Sachs says.

Cognitive impairment could be linked to death risk in a number of ways, he says. Those with it may be at risk for other problems, such as falls. They may be less likely to follow instructions to take medicine for other chronic conditions. They may be less likely to follow instructions to eat a healthy diet, increasing their risk of health problems.

Memory and Thinking Problems and Risk of Death

The new study is ''another piece of evidence that mild cognitive impairment is far from a benign condition," says Terry E. Goldberg, PhD, an investigator at the Feinstein Institute for Medical Research and professor of psychiatry and behavioral science, Hofstra North Shore-LIJ School of Medicine.

In his own recent research, Goldberg has found that cognitive information is more accurate at predicting who will progress to Alzheimer's disease than are such changes as brain volume.

To reduce the risk of impairment, he says that physical activity has been shown to have good effects on brain chemicals that affect memory.

"There's some evidence that mental activity over the course of one's life span is certainly effective," he says. A healthy diet is also advised. Goldberg reports research grants from Pfizer and serving as a consultant for Merck.

The findings lend support to the idea that cognitive impairment is not something to be dismissed, says William H. Thies, PhD, chief medical and scientific officer for the Alzheimer's Association. "This paper is really a very solid piece of research work that really is documenting that the more cognitive impairment you have, the sooner you are going to die," he tells WebMD. "We have to start taking dementia seriously and recognize it as a fatal disease."